With continuous development of mobile communications technologies, requirements for positioning services are also increasing. A positioning technology is a technology used to determine a geographic location of a mobile terminal. In a mobile communications network, a location server may obtain location information of a mobile terminal directly or indirectly by using a wireless communications network resource. Currently, standard terminal positioning modes used in long term evolution (LTE) include enhanced cell identity (e-CID) positioning, observed time difference of arrival (OTDOA) positioning, and the like.
The e-CID positioning is mainly to obtain a geographic location of a target terminal through calculation according to an identity (ID) of a cell in which the target terminal is located, a time difference between reception and transmission by the target terminal, a time difference between reception and transmission by a serving base station, and an angle of arrival (AOA) of a signal transmitted by the target terminal and received by the serving base station. The OTDOA positioning is a network-assisted terminal positioning technology. Its implementation process is as follows: After an enhanced serving mobile location center (e-SMLC) on a network side is notified of transmission and reception configurations of a positioning reference signal (PRS) specified by a base station and a mobile terminal, the base station sends a downlink PRS. The mobile terminal receives PRSs from a plurality of positioning base stations, and after identifying a location of a first-arrival path of each PRS, the mobile terminal may obtain a time difference of arrival of the PRSs between different base stations, and then the mobile terminal reports the time difference of arrival of the PRSs between different base stations to the e-SMLC. After receiving the time difference of arrival of the PRSs between different base stations, the e-SMLC multiplies the time difference by a velocity of light through hyperbola model calculation to obtain a difference of distances between the mobile terminal and different base stations. After a difference of distances between the mobile terminal and two base stations is obtained, a positioning hyperbola may be constructed, and an intersecting point between two positioning hyperbolas is a location of the mobile terminal. In this way, the e-SMLC may finally obtain the accurate location of the mobile terminal.
In the foregoing two positioning methods, when a same cell ID is shared by a plurality of base stations (for example, in some areas, some base stations for transmission assistance or small cells are deployed and used for coverage or capacity enhancement, and these small cells have a same cell ID), if positioning is performed according to the e-CID positioning method, poor positioning accuracy is caused finally. In the OTDOA positioning method, a PRS signal sequence is obtained according to a cell ID. Likewise, when a same cell ID is shared by a plurality of base stations, for the mobile terminal, PRSs sent by the plurality of base stations are the same. Therefore, there is also a problem of poor positioning accuracy.